The world is divided into Zones for the purpose of purchasing and playing DVDs.
For your guidance Zone 1 is the USA, Zone 2 is the UK, Zone 4 is Australia and Zone 0 is all zones, meaning the discs will play anywhere in the world.
It is possible to re-programme some older DVD players to turn them into all region players. Log onto www.videohelp.com/dvdhacks and if your make and model number is on the site, follow the instructions to change.
Most DVD players sold recently are all zones even though they are marked Zone 4. Please check with your retailer All DVDs on this site are all zones unless stated otherwise.